Two-year colonization stability of the JP2 clone of Aggregatibacter actinomycetemcomitans

A particular clone (JP2) of Aggregatibacter actinomycetemcomitans is likely to be an important etiological factor of aggressive periodontitis. However, little is known about the stability of infection with the JP2 clone of A. actinomycetemcomitans.

Objectives: The aim was to obtain information about the colonization dynamic of the JP2 clone and to analyze the association between long-term infection profiles of the JP2 clone and development of aggressive periodontitis.

Methods: Periodontal plaque samples were collected from 365 Moroccan juveniles at baseline and after one and two years follow up. The samples were subsequently analyzed for presence of the JP2 clone of A. actinomycetemcomitans by PCR. Periodontal attachment loss was measured at baseline and at the end of the follow up period.

Results: At baseline 43 (12%) individuals were positive for the JP2 clone. During the two-year follow up period a nearly halving of the carriers of the JP2 clone was found (7% carriers at follow up). In 44% of the JP2 clone carriers at baseline the clone was demonstrated also at the two-year follow up.

Relative risks for development of aggressive periodontitis were 5.2 [95% CI: 2.8; 9.8], 9.7 [95% CI: 5.3; 17.9], and 11.5 [95% CI: 7.3; 18.2] for individuals with presence of the JP2 clone at one, two, or three plaque sampling sessions during the two-year follow-up period, respectively. The relative risks were not changed substantially if they were adjusted for concomitant presence of other genotypes of A. actinomycetemcomitans.

Conclusion: Nearly half of the JP2 clone carriers at baseline were positive at one or more sampling sessions during the two-year follow up period, whereas the JP2 clone appeared to colonize only transiently in a substantial part of the carriers. The role of the JP2 clone as an important etiological factor in aggressive periodontitis was further substantiated.